I don't find the transition back and forth from motorcycling to bicycling difficult but I do find that when switching between the two seems to help increase my riding skills on both. When I switch from the motorcycle to the bicycle, I tend to take corners faster because it is so easy to lean even my 30lb Surly after dragging a 400lb Ducati around turns. Back on the moto, I get more confidence in turns because I realize how much lean you can actually put into a bike (motor or no motor). It's kind of a symbiotic relationship; I remember reading how a lot of mountain bike racers also train with motorcross/off-road motorcycles to increase their bike-handling skills.